The bioengineer who wants to return mobility to people with spinal cord injuries

BarcelonaThe day she arrived at the laboratory and saw that the mice were moving again, Zaida Álvarez (Barcelona, 1984) could not help but shudder. Behind her lay more than six years of research, from Monday to Sunday, and a risky bet to outsmart evolution and repair the irreparable: the central nervous system of a mammal. "It was mind-blowing. Those animals, which had a severe spinal cord injury and were paralyzed, were walking again," she recounts, still moved, this bioengineer and researcher at the Institute for Bioengineering of Catalonia (IBEC).

At the time, she was working at Northwestern University, in Chicago, in the laboratory of the Nobel-nominated bioengineer Sam Stupp, with the goal of developing a biomaterial capable of regenerating the spinal cord and recovering motor function after severe injuries. But Álvarez had already delved into this pioneering field long before, in Barcelona, during her master's degree in biomedical engineering (UB-UPC). "At that moment, the concept of regenerative medicine didn't even exist, and that was where I fell in love with the tissue engineering subject." So much so that she has dedicated her professional career to it and has become one of the prominent researchers worldwide working at the frontier of tissue engineering and nervous system regeneration.

In this story, a professor, fellow IBEC bioengineer Elisabeth Engel, was key. With her, Álvarez began to develop biomaterials to implant into the brains of mice and repair lesions caused by impacts. "This in 2008 was almost science fiction," she recalls. "When I presented our results at conferences, people were amazed."

Rebuilding after an earthquake

From the brain, she moved on to focus on the spinal cord. When an injury occurs, there is hemorrhaging and cell death, especially of neurons. Immediately, astrocytes—a type of nerve cell—begin to form a scar around the wound to prevent the damage from spreading. This patching, which is crucial for survival, prevents neurons on either side from reconnecting and allowing movement to be regained.

"Like a road that has been destroyed after an earthquake. You need bridges to reconnect the two parts," says Álvarez. And this is what she tries to do with biocompatible materials, such as the hydrogels she has developed, which reproduce the environment where cells live so they can colonize it. "We need the highway, which is the biomaterial, but also to put up signs, like traffic signs so that drivers and nerve cells know where to go."

In Chicago, she had already developed a biomaterial that enabled mice to regain movement and that the American drug agency, the FDA, has designated as an orphan drug, a distinction that gives access to various incentives to facilitate the development of treatments for rare diseases. A first step towards approval. And now, from the IBEC, Álvarez wants to go beyond mice. With the Spinecraft project, funded with a prestigious European ERC Consolidator grant of 2.8 million euros, she is working to build a synthetic model of the human spinal cord using high-resolution 3D bioprinting and cells derived from patients with amyotrophic lateral sclerosis (ALS).

“The idea is to have a living laboratory where we can study the disease and test possible treatments before reaching a clinical trial with people,” notes this researcher. In this sense, she is also developing vascularized organoids—mini-spinal cords—to test drugs for spinal cord injuries, thanks to the funding of almost one million euros from the CaixaResearch Health call. The mouse that started moving its legs again was a small but great victory. But the real challenge is to translate this success to humans and manage to get a person out of a wheelchair. Between both things lies the science that Álvarez does, cell by cell.